Preparation Process of Straw-based Activated Carbon for Uranium Wastewater Treatment

Abstract

A process and equipment for preparing activated carbon from straw and its application in treating uranium wastewater are proposed. The ZnCl2-microwave carbonization method is adopted, which flexibly applies the wave absorbing ability of zinc element and greatly reduces the carbonization time. At the same time, the dehydrogenation of ZnCl2 limits the formation of coal tar and improves the carbon formation rate. Through citric acid modification, a functional group with specific adsorbability to uranyl ions is formed, which can produce high-efficiency complexation effect with uranyl ions and improve the adsorption capacity of uranyl ions. When the wastewater is mixed with other heavy metal elements, uranyl ions occupy the main adsorption sites, which can still maintain excellent targeted adsorption effect and can be targeted to treat uranyl ions in radioactive uranium wastewater. The key equipment in the process consists of cleaning and impurity removal components, raw material crushing components and carbonization components. The whole production process is completed in the same equipment. The optimum adsorption capacity (Ac) of 4.98 mg/g and uranium adsorption rate (Ar) of 99% were obtained by using soybean straw as raw material under the preparation conditions of 20% ZnCl2 solution and 15% citric acid solution.